Compared with the conventional two-dimensional plane display technology, the three-dimensional imaging technology provides more vivid three-dimensional images, and therefore has become the mainstream of development in display technology. So far, liquid crystal display devices (LCDs) have become major selections for various industries and even home entertainment displays because of such advantages thereof as light and handy appearances, low power consumption, zero radiation and the like. Accordingly, three-dimensional imaging LCDs which are developed based on the original two-dimensional display technology have become a new hot spot to be developed.
The common three-dimensional imaging technology is currently shutter glasses technology. This technology uses a time-division effect, so that left-eye and right-eye lenses of three-dimensional glasses are alternatively switched on in turn. When the right-eye lens is on, the liquid crystal display device outputs an image to be supplied to the right-eye; and when the left-eye lens is on, the LCD outputs an image to be supplied to the left eye. Then, an image viewer, based on the angle difference between viewing angles of the left and right eyes, may synthesize the left-eye and right-eye images in his/her brain to produce a three-dimensional image with depth of field and hierarchical perception.
In the liquid crystal display device, the liquid crystal molecules are generally driven to rotate by alternating current, and the rotation angle of the liquid crystal molecules is changed to enable image display of different gray scales. The reason for such a driving manner is that in case direct current were used to rotate the liquid crystal molecules, mobile ions inside the liquid crystal molecules would move in the same direction, so that another electric field would be generated and thus interfere the rotating direction of the liquid crystal molecules. That is, residual direct current would appear. Typically, to avoid the quality of image display being affected by such residual direct current, voltages exerted on a pixel electrode of a pixel unit should be changed periodically in the liquid crystal display through switch between the positive polarity and the negative polarity of a data signal of image information. However, for the three-dimensional liquid display crystal panel which co-works with the shutter glasses, if a polarity inversion driving method in terms of single-frame is used to switch between the negative polarity and the positive polarity of the data signal of image information, residual charge would appear, which is similar to the case of using residual direct current, thus causing a three-dimensional image sticking (IS).
It is assumed that there is a liquid crystal display device of 256 gray scales, in which a bright screen pervious to light (a white picture with 255 gray scales) is marked as L255, while an opaque, dark screen (a black screen with 0 gray scale) is denoted as L0. Positive and negative driving voltages for the white screen are 7 V and 5 V respectively, and for the black screen, the positive and negative driving voltages are 1 V and 11 V respectively. A common electrode voltage is 6 V. Then, with respect to a certain pixel electrode in the panel, Table I, shown in FIG. 4A, shows changes of a voltage exerted on the pixel electrode and its voltage difference from the common electrode.
It can be seen from Table I that, in this case, the difference of voltage of the pixel electrode relative to the voltage of the common electrode ranges from 1 V to 5 V. That is, a voltage exerting on the liquid crystals is 1 V during a positive polarity driving period, and 5 V during a negative polarity driving period. As the voltages exerted on the liquid crystals during the positive and negative polarity driving periods differ considerably and both present as positive, they cannot cancel each other out, such that the residual charge which is similar to the residual direct current would occur after a long time operation. This leads to a three-dimensional image sticking.
To avoid a three-dimensional image sticking, in the prior art, a polarity inversion driving method in terms of double-frame is used for switching between positive polarity and negative polarity of the data signal of image information. In this driving method, since the polarity of the data signal is switched over every two frames, the voltage of the pixel electrode and its difference from the common electrode respectively vary as shown in Table II, shown in FIG. 4B.
According to Table II, the voltage difference of the pixel electrode relative to the common electrode, under this situation, repeatedly switches in the cycle of 1 V→−5 V→−1 V→5 V. That is, during the positive polarity driving period, voltages applied to the liquid crystals are 1 V and −5 V; and during the negative polarity voltage driving period, the voltages are −1 V and 5 V. The voltage difference of the pixel electrode relative to the common electrode during the positive polarity driving period may counteract that of the pixel electrode relative to the common electrode during the negative polarity driving period, so that the image sticking can be eliminated. However, this further brings about uneven luminance between the left and right eyes. Such a problem is more conspicuous especially for the liquid crystal display panel which uses charge-sharing technique (LCS) to eliminate the color shift. The reason for the uneven luminance is that, in the liquid crystal display panel, in order to eliminate the color shift due to a large viewing angle, the pixel electrode of each pixel unit is typically divided into two portions, i.e. a main area (Main) and a sub area (Sub), and the pixel unit is provided with a sharing capacitor, such that the charges at the main and sub areas are re-distributed under the control of a control signal, so as to change the voltages of the main and sub areas. Since the charge sharing capacitor has a capability of charge storage, on the one hand, a new frame of image would be brighter due to the charge accumulation effect when the charge obtained by the sharing capacitor during the new frame of image has the same polarity as the charge stored during the previous frame. On the other hand, when the charge obtained by the sharing capacitor during the new frame of image presents opposite polarity against the charge stored in the previous frame, the new frame of image would be darker because of charge counteraction. Therefore, under the same input data signal (e.g., an input signal L255 as shown in Table III, shown in FIG. 4C), the luminance of an image for the left-eye is always weaker than the luminance of an image for the right-eye when output by the liquid crystal display panel is based on the polarity inversion driving method in terms of double-frame.
In response to these problems mentioned above, provided by the present disclosure is, through repeated research and experiments, an array substrate and a liquid crystal display panel that are capable of eliminating the luminance difference between the left and right eyes, and a method for driving the liquid crystal display.